The present invention is particularly useful in automobiles which use internal combustion engines. Manufacturers of such engines have been concentrating for some time in making them more efficient while at the same time reducing the overall weight to improve the efficiency of the automobile generally. One source of lost energy is the valve train. The weight of the moving parts and the friction they exhibit both work to reduce the efficiency of the engine. More particularly, if the weight can be reduced, then the power lost in accelerating these parts through a cycle will also be reduced. Although some advances have been made, manufacturers still strive for improvement in this area because energy lost in the valve train can not be recovered.
In the past, stamped steel rocker arms have been used instead of heavier forged or cast iron, and it has become common practice to use roller bearings to reduce friction. With the advent of overhead cam systems, there has been a need for arms designed to be supported at one end and to respond to a cam engaging the central section of the arm to deflect the free end into engagement with a valve stem. Such devices are known generally as "finger followers" and this invention is directed to such structures.
Finger followers have developed to the point where it is common practice to mount a central roller bearing to act as a cam follower. The bearing is relatively large and this has caused some design problems resulting from the length of the follower and the need for rigidity despite the weakness created by accommodating the roller bearing.
Examples of state-of-the-art followers are to be found in U.S. patent Ser. Nos. 4,614,171; 4,697,473; 4,872,429; 4,995,281; 5,048,475 and 5,010,856.
Another consideration is the engine head. Overhead valve arrangements result in some complexity in the block due to the fact that hydraulic posts must be accommodated for one end of the finger followers in the general area of the valves themselves. If the posts and valves can be moved closer together, then the amount of material necessary in the engine head can be reduced because there is less material needed to accommodate the parts.
For these and other reasons, a short, light and rigid finger follower would be desirable.